start method
Begins capturing and encoding data to the file specified with setOutputFilePath.
Call this after prepare.
If applications set a camera via setCamera, the apps can use the camera after this method call. The apps do not need to lock the camera again. However, if this method fails, the apps should still lock the camera back. The apps should not start another recording session during recording.
Implementation
Future<void> start() => _channel.$start(this);